Metering pump



July 11, 1967 J. H. BUMS'TEAD 3,330,218

METERING PUMP Filed June 11, 1965 I N VEN TOR.

JAMES h. fiz/Msrfno United States Patent 3,339,218 METERING PUMP James H. Bumstead, 2750 Orange St., Riverside, Calif. 92501 Filed June 11, 1965, Ser. No. 463,285 9 Claims. (Cl. 103--234) My invention relates to an improvement in metering pumps for liquids, and more specifically to an improvement in slurry feeders for diatomaceous earth filtration systems.

Frequently, chemical solutions and slurries are required to be pumped at a determined rate, and for this purpose a positive displacement piston or diaphragm pump is used. The pumping rate is usually adjustable by varying the length of stroke. Pumps of this kind produce a pulsating flow of variable capacity per stroke. Other positive displacement type pumps adjust the pumping rate by varying the frequency of pulsation, keeping the capacity per stroke constant. Experience has shown that pumps of both of these types, when pumping abrasive slurries, especially at high pressures, need frequent replacement of moving parts that are in contact with the fluids.

At the present state of the art, other means of pumping chemical solutions and slurries at determined rates, frequently use an eductor to suck the slurry into the pressure pipeline, and centrifugal or turbine pumps for boosting. The means for accurately proportioniug the chemicals is done on the suction side of the eductor by means of pulsating valves, automatic dry feeders, or the like. Fre

quently, in such systems, the pressure downstream of the eductor is such that a booster pump must be located in the pipe which carries the chemical. The eductor and booster pumps commonly used for these applications, when handling abrasive slurries, especially at high pressure, are subject to excessive wear. The abrasive slurry is also reduced in quality after having passed through the eductor and pump.

It is therefore a major object of my invention to provide a metering pump that has no moving parts in contact with the liquid being pumped, thus reducing maintenance costs.

Another object of the invention is to provide a metering pump that will not break down slurries by turbulent action of pistons, diaphragms, impellers, jets, and the like.

Still another object of the invention is to provide a metering pump that will automatically control the body feed in a diatomaceous earth filtration system.

Another object of the invention is to provide a metering k pump that will produce a continuous instead of a pulsating flow.

These and other objects of my invention will become evident from the following description of the preferred V embodiment of the same, reference being had to the accompanying drawing, which shows a schematic representation of a diatomaceous earth filtration system having a slurry feeder for body feed.

The drawing shows a diatomaceous earth filter 1 with.

infiuent header 2, efiluent header 3, and drain pipe 4, which are of standard construction. The filter, for purposes of illustration, is an automatic backwash type that has valves controlled by electrical, hydraulic, or pneumatic means, which are not shown since they are not a part of this invention.

The body feed system for this filter is illustrated in detail to show my method and means for pumping and controlling the flow of body feed to the filter. It consists generally of a gravity slurry tank 14, a refill tank 13, a slurry feeder 12, a booster pump 8, and assorted pipes and valves. The gravity slurry tank 14 is of standard construction, with agitator, drain, water supply and loading hatchway, the details of which are not shown for brevity.

In operation, a slurry is mixed in the gravity slurry tank 14 once a day or so. The slurry then automatically flows into the refill tank 13 until said refill tank is full, then air pressure is applied on top of the slurry to force it out of the refill tank 13, and into the feeder tank 12. The feeder tank 12 is continually under pressure by compressed air which is forcing the slurry out of the feeder tank through a meter tube 39 and into the body-feed pipeline 5 which carries it to the influent to the filter to mix with the turbid fluid.

Although not essential to this invention, I have illustrated a preferred method of diluting the slurry to keep the slurry pipe 5 from plugging, by means of a booster pump 8 which takes water from the influent header 2 by suction pipe 7, and boosts it into the high pressure water header 9 and thence into the flush water supply line 11, which leads to the slurry feeder, and is injected through throttle valve 40 just downstream of the slurry outlet valve 29. 7

Although not essential to my invention, I have illustrated a means for automatically diluting the slurry in the slurry feeder tank 12, to compensate for varying turbidity of flow through the filter. A control panel 49 having a ditferential pressure measuring device which is connected across the filter elements by pressure-sensing lines 46 and 47, automatically programs the operation of the valves on the slurry feeder tank 12 and refill tank 13. The method and mechanism of the control panel is illustrated in my co-pending application Ser. No. 226,981, dated Mar. 20, 1964, now abandoned. The principle of operation of the system is that each time the pressure differential in the filter reaches one of several predetermined pressure settings, the slurry feeder tank would automatically fill with water to a certain level, and then fill with slurry from the refill tank to a certain level, during which time the slurry would continue to flow at a constant rate out of the slurry feeder tank 12, and into the influent to the filter 2. The elapsed time it takes for the differential pressure across the filter to reach the next higher pressure setting, depends upon the rate of flow and the filterability of the fluid, which may be variable. Since the rate of flow of slurry out of the slurry feeder is constant, the amount of slurry left in the slurry feeder tank after said variable elapsed time would also be variable. Thus a variable amount of water which is proportional to the elapsed time, would be added to the slurry to bring it up to a certain level, and a definite amount of slurry would be added to bring it to the next certain level. Thus, each time one of the pressure differential levels is reached, the slurry feeder is refilled with a variable amount of water and a definite amount of slurry. This will vary the concentration of the slurry in the slurry feeder tank in response to the rate at which the filter is plugging. The faster the filter is plugging, the less water is added to the slurry feeder tank, and the more concentrated the slurry will become, thus compensating for the fast rate of plugging of the filter.

As stated before, the automatic dilution feature is not essential for my invention. If desired, the body feed rate may be held constant by causing the refilling cycle of the slurry feeder to be triggered by the slurry reaching a certain level in the slurry feeder tank. Thus, there would always be a definite amount of water and a definite amount of slurry added to the tank. In a more simplified version of this type, the step of adding Water to the slurry feeder tank could be eliminated, and only a certain quantity of slurry would be added when needed.

Many other variations of this principle will be obvious to those skilled in the art. A detailed description of the mechanism for accomplishing the above operation follows:

Typically a filter plant consists of two or more filters with a slurry feeder tank 12 for each filter, but only one refill tank 13, one gravity slurry tank 14, and one high pressure water system with a booster pump 8, and an air compressor (not shown). To ready the plant for service, the gravity slurry tank 14 is filled with filter aid slurry of the proper concentration. The slurry agitator motors 19 and 31 are started; pump 8 is started; and the control panel for those filters which are desired to be put into automatic service are selected by manual selector switches. Fromthen on, the filters selected will automatically come on in sequence, automatically wash, precoat, recirculate, fill the slurry feeder 12, and go on stream, with the slurry feeder 12 going on stream too. The panel control 49 controls all of the functions of the filter unit and the body feed system.

Initially the filter 1 is washed, precoated, .and recirculated in the standard manner. The booster pump 8 is in service supplying high pressure water from suction line 7 to a high pressure water header 9 which also supplies the other filters in the plant (not shown). The dilution water circulates through flush Water supply line 11 and throttle valve 40, slurry supply line 5, and into the infiuent header upstream of the influent valve 6, which is closed during the. recirculation cycle. Slurry outlet valve 29 is initially closed so that no slurry is being fed vwastefully into the system during the recirculation cycle of the filter.

Before any of the filters are ready to go on stream, the refill tank 13 is filled in preparation for service by the following means: The control panel 49, by means of time switch. or other appropriate device in the filter sequence sends an initial signal through control line 48 to open the slurry inlet valve 21 to refill the tank, which allows slurry to flow through pipe 15 by gravity, or other means not shown, into the refill tank 13. Air is displaced by the slurry and flows out of valve 22 through pipe 18. Valve 26 at the top. of outlet pipe 16 from the refill tank is open so that air may be displaced as the slurry seeks its level in this pipe during filling of the refill tank 13. The

agitator blade 20, driven by motor 19, keeps the slurry in suspension and all of the pipes that carry slurry should be designed to allow the slurry to drain back into the agitated tanks, thus preventing plugging of the lines. When the level of the slurry in the refill tank reaches the high probe. 41, a control signal is sent to the panel 49, and the 'control panel responds by sending out a signal closing slurry inlet valve 21 to the refill tank, and air outlet valve 22 in the refill tank, and also closing outlet valve 26. The refill tank 13 is now ready for service.

The. slurry feeder tank 12 is initially full of air at i atmospheric pressure and all valves except air outlet valve 27 are closed. The. slurry level probes 42, 43 and 44 are dry. When a filter unit is selected to be put in service, the slurry feeder tank is also readied for service by starting the agitator motor 31. When the controller 49 receives the, signal that the refill tank 12 is ready for service, the

air inlet valve to the refill tank 23 is opened, allowing compressed air to: flow from air supply header 45, through a rate-of-flow valve 24 and pipe 17 into the refill tank 13. This air pressure forces the slurry up into the slurry feeder tank 12 through pipe 16. The slurry inlet valve to slurry feeder 25 is then opened and the compressed air pushesv the slurry into the slurry feeder tank 12 at a constant rate. The air in the slurry feeder tank is dispelled out through the air outlet valve 27. When the slurry reaches the probe 42, slurry inlet valve 25 and air outlet valve 27 to the slurry feeder tank close. The slurry feeder is ready for service.

It may be seen by those skilled in the art that diatomaceous earth slurries, handled by air pressure in the fashion described, will not be broken down by the action of moving parts such as impellers or jets or pistons. The device for controlling the rate. of flow of slurry is an air regulating valve 32, which may be of the constant pressure, constant flow type, or constant differential pressure type, or any other type consistent With the way the rate of flow of slurry is to be controlled. The air regulating valve 32 provides a low maintenance means of metering the slurry, since the abrasive slurry does not pass through moving parts. The standard air regulator is also easily 7 adjusted for varying the rate of flow of slurry when desired.

The flow of the slurry out of slurry feeder 12 into filter tank 1 will not be intermittent or pulsating flow. The uniform flow of air into the slurry feeder tank 12 will maintain a uniform flow of slurry out of the feeder. It Will be shown later, how the slurry flow is maintained even while the slurry feeder tank is being refilled by means of refill vessel 13.

When slurry feeder tank 12 is in service, the rate of flow of compressed air into the tank through regulating valve 32 must equal the rate of flow. of slurry out of the tank through meter tube 39. As the slurry in tank 12is used up, normally it'will be desirable to refill the slurry feeder tank 12 while it is in service and without substantially changing the rate of flow of slurry through meter tube 39. When the slurry feeder tank is to be refilled With slurry, some of the compressed air in the tank must be the slurry under pressure into the slurry feeder tank 12 at a uniform rate. The air Which flows out of slurry feeder tank 12 through valve 27 should be approximately equal to the rate at which the slurry is entering the tank, and for this purpose valve 27 may have an adjustable stop to keep it from opening all the way.

It may be impractical and/or unnecessary to adjust the air release from the slurry feeder tank 12 through valve 27 to exactly equal the inflow of slurry from the refill tank as controlled by air-flow valve 24. Air regulating valve 32 will either increase or decrease its air flow in order to maintain a constant flow of slurry through meter tube 39. i 7

When the slurry feeder tank 12 is filled, the refill tank .13 then is refilled as follows: Air inlet valve 23 closes, and air outlet valve 22 opens, releasing air pressure from the tank. Air valve 26 opens, allowing slurry to drain' back into the refill tank and seek its level. Slurry inlet valve 21 opens, allowing refill tank 13 to againfill as before. I 7

Now that the slurry feeder tank 12 is ready for service, at an appropriate time just before the filter 1 goes on stream, the slurry feeder is put in service as follows: Air inlet valve 23 is opened, allowing compressed air to flow through regulating valve 32 into the slurry feeder tank 12. Slurry outlet valve 29 is opened and the compressed air forces the slurry out to the filter 1. In passing through meter tube 39, the restriction of flow of slurry causes a pressure drop across the meter tube, and that pressure drop is sensed by sensing lines 35 and 36. I have illustrated here a bubbler arrangement to keep the slurry from getting into the sensing lines 35 and 36, by means of check 7 influent pipe 2. The flow of air in the sensing lines is controlled by valves 33 and '37,which are standard air flow control valves. The differential pressure across the meter tube is used ina standard manner to control the flow of air through regulating valve 32, and thus maintains a constant flow of slurry through the meter tube 39. Thus the body feed system continues to operate until either the slurry tank 12 needs to be refilled,.or the filter 1 is turned off or backwashed.

As filtration proceeds, the pressure differential builds up across sensing lines 46 and 47, and the pressure differential device in control panel 49 rotates a program switch which initiates the refill action as follows:

The slurry in slurry feeder tank 12 has reached some undetermined level, say between probes 43 and 44, when the command signal is received to refill. Since probe 43 is dry, water inlet valve 30 will open, allowing water, from high-pressure water header 9, to enter the slurry feeder tank through pipe 10, until the level reaches probe 43. Water valve 30 then closes, and slurry inlet valve 25 opens, allowing the slurry to fill to the level of probe 42. In order to fill the slurry feeder tank in this fashion, without disturbing the flow of slurry past the meter tube 39, air outlet valve 27 on top of the slurry feeder tank is opened to allow the displaced air to escape to the outer atmosphere. The air outlet valve 27 is then closed and slurry inlet valve 25 is closed, thus returning slurry feeder tank 12 to normal service.

If the automatic slurry dilution feature is not used, the slurry feeder refill cycle is initiated by probe 44 becoming dry, and the water fill is omitted.

Several variations and different applications of my invention may occur to those skilled in the art without departing from the spirit and scope thereof, and therefore this disclosure is not to be limited by the precise details shown in the drawings or particularly described in the specification by way of example, but only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A liquid transfer device comprising a pressure vessel having;

a liquid inlet pipe adapted for connection to a source of liquid to be metered;

a gas outlet pipe connected to the upper portion of said pressure vessel, for venting gas expelled from the pressure vessel while the latter is being filled with liquid;

a gas inlet pipe adapted for connection to a source of pressurized gas, and having gas regulating valve means operable to control the flow of pressurized gas into the liquid-filled pressure vessel;

a liquid outlet pipe connected to the lower part of the pressure vessel, and having a liquid metering device provided therein; and

control means operatively connected to said gas regulating valve for controlling the flow of gas into said pressure vessel responsive to the metered outflow of said liquid through said outlet pipe.

2. A liquid transfer device as described in claim 1, wherein the liquid metering device is a differential pressure producing device;

and wherein said gas regulating valve means is of the type operable to regulate the flow of gas responsive to the differential pressure produced across said liquid metering device.

3. A liquid transfer device comprising a pressure vessel having;

a liquid inlet pipe adapted for connection to a source of liquid to be metered;

a gas outlet pipe connected to the upper portion of said pressure vessel, for venting gas expelled from the pressure vessel while the latter is being filled with liquid;

a gas inlet pipe adapted for connection to a source of pressurized gas, and having gas regulating valve means operable to control the flow of pressurized gas into the liquid-filled pressure vessel;

a liquid outlet pipe connected to the lower part of said pressure vessel, and having a liquid metering device provided therein, said liquid metering device including a device producing a pressure differential between,

two points in said liquid outlet pipe;

a high pressure sensing line connected to said liquid outlet pipe on the high pressure side of said differential pressure producing device;

a low pressure sensing line connected to said liquid outlet pipe on the low pressure side of said differential producing device;

control means connected to said sensing lines and operatively connected to said gas regulating valve for controlling the flow of gas into said pressure vessel, said gas regulating valve means being of the type operable to regulate the flow of gas into said pressure vessel responsive to the pressure differential; and

means for preventing liquid from entering said sensing lines, said means comprising a source of gas under pressure connected to said high and low pressure sensing lines, whereby gas is forced through said sensing lines and bubbles into said liquid outlet pipe, said differential regulating valve being operable responsive to the differential pressure in said sensing lines.

4. A liquid transfer device comprising a pressure vessel having:

a liquid inlet pipe adapted for connection to a source of liquid to be metered, said inlet pipe having first valve means provided therein;

a gas outlet pipe connected to the upper part of said pressure vessel, for venting gas expelled from the pressure vessel while the latter is being filled with liquid, said outlet pipe having second valve means provided therein;

a gas inlet pipe adapted for connection to a source of pressurized gas, and having gas regulating valve means operable to control the flow of pressurized gas into the liquid-filled pressure vessel;

a liquid outlet pipe connected to the lower part of said pressure vessel, and having a liquid metering device provided therein; and

control means operatively connected to said gas regulating valve for controlling the flow of gas into said pressure vessel responsive to the metered outflow of said liquid through said outlet pipe; and

level sensing means operatively connected to said first and second valve means to refill said pressure vessel to a prescribed high level when a prescribed low level is reached, while maintaining uninterrupted flow of slurry out of the pressure vessel.

5. Apparatus for liquid metering by displacing the liquid from a pressure vessel by means of a gas, with provision for refilling the pressure vessel with liquid, comprising:

( l) a first pressure vessel having:

(a) a liquid inlet pipe and associated valve means connected to a source of liquid to be metered;

(b) a gas outlet pipe and associated valve means for venting the gas being displaced during the filling of the vessel with liquid;

(c) a gas inlet pipe and associated gas regulating and shutoff valve means connected to a source of pressurized gas, for supplying the pressurized gas to the pressure vessel;

(d) a liquid outlet pipe near the bottom of said first pressure vessel;

(2) a sec-0nd pressure vessel having:

(a) a liquid inlet pipe and associated valve means connected to the liquid outlet pipe of said first pressure vessel, for receiving the liquid therefrom;

(b) a gas outlet pipe and associated valve means for venting the gas which is displaced during filling of the second pressure vessel;

(c) a gas inlet pipe connected to a source of pressurized gas and having a shutoff valve means, and regulating valve means suitable for maintaining a substantially uniform outflow of liquid being displaced by the gas; and

(d) a liquid outlet pipe with associated valve means. I

6. Apparatus for feeding body feed in a filtration system, comprising:

a of' (l) a gravity slurry tank for containing the body feed slurry;

' (2) a first pressure vessel having a slurry inlet pipe connected to said gravity slurry tank, and having valve means for filling said pressure vessel with slurry by gravity;

(3) a gas vent pipe in the first pressure vessel having valve means for venting the gas displaced by the slurry inflow;

(4) asource of pressurized gas;

(5) a gas inlet pipe in said first pressure vessel connected to said source of pressurized gas and having valve means controlling the flow of pressurized gas into the first pressure vessel for displacing the slurry in a controlled manner;

(6) a slurry outlet pipe near the bottom of said first pressure vessel connected to the slurry inlet of a second pressure vessel, having valve means for stopping the flow of slurry and for venting the slurry out. "let pipe;

(7) a gas outlet pipe in the top of the second pressure vessel having valve means for expelling the gas displaced while filling the second pressure vessel;

(8) a gas inlet pipe in the second pressure vessel connected to said source of pressurized gas and having regulating and control valve means for controlling and regulating the flow of pressurized gas into the second pressure vessel, thereby maintaining the outflow of displaced slurry at a substantially uniform rate; V

(9) a liquid outlet pipe near the bottom of the second pressure vessel, having valve means for stopping the flow of slurry out of the second pressure vessel, said liquid outlet pipe connecting to the influent to the filter for mixing the slurry with the liquid being filtered;

(10) a first control means for opening the slurry inlet and gas outlet valves to the first pressure vessel for filling the first pressure vessel;

(11) a first liquid level sensing device located near the top of said first pressure vessel having control means for closing the slurry inlet valve and gas outlet valve to the first pressure vessel when the liquid has reached the level sensing device;

(12) second control means for opening the gas inlet valve to the first pressure vessel, and opening the slurry inlet and gas outlet valves to the second pressure vessel for filling the second pressure vessel While the filter is being prepared for service;

(13) a second liquid level sensing device located near the top of the second pressure vessel and operatively connected to a third control means to close the slurry inlet valve and gas outlet valve to the. second pressure vessel, and closing the gas inlet valve, and opening the slurry inlet valve and gas outlet valve to the first pressure vessel when the slurry level reaches said second liquid level'sensing device;

(14) fourth control means for opening the gas inlet and slurry outlet valves to the second pressure vessel, thus allowing slurry to flow to the filter when the filter goes on stream, and for closing the gas inlet and slurry outlfit valves when the filter goes ofi stream for backwas 7. A method of metering liquids, comprising the steps (1) filling a pressure vessel to a desired level with the liquid to be metered thereby displacing gas out of the pressure vessel during the filling process;

(2) pressurizing the liquid in the pressure vessel with gas, thereby causing the liquid to flow out of the pressure vessel through an outlet pipe;

(3)' netering the rate of outflow of the displaced liq- 1(4) continuously regulating the inflow of pressurized 8 r gas'as a function of the outflow rate of said liquid, whereby the quantity of gas admitted to said pressure vessel is such as to maintain a constant liquid outflow rate. 8-. A method of continuously metering a liquid, comprising the steps of:

the second pressure vessel with gas and thereby forcing the liquid contents out of the second pressure vessel at a substantially uniform rate; a

r (5) refilling the first pressure vessel in the same manner as step 1; and

(6) at any desired time before the liquid contents of V tem, comprising:

a source of diluent;

a source of body feed;

a source of pressurized gas;

a first pressure vessel operably connected to said source of body feed for periodically filling said first pressure vessel with said body feed, and operably connected to said source of pressurized gas for periodically pressurizing said first pres-sure vessel containing said body feed; a

a second pressure vessel operably connected to said first pressure vessel for receiving therefrom said body feed which is displaced by saidpressurized gas, and operably connected to said source of pressurized gas for pressurizing said second pressure vessel, and operably connected to a filter for delivery thereto of said body feed which is displaced by said pressurized gas,

and a diluent inlet pipe operably connecting said second pressure vessel to said source of diluent;

a pressure differential measuring device operably connected across said filter;

control means operably connected to said pressure differential measuring device and said first and second pressure vessels for filling said second pressure vessel with diluent to a predetermined intermediate level when the pressure differential reaches a predetermined value, and when the level of body feed is below said intermediate level, and then filling said second pressure vessel to a predetermined high level with body feed from said first pressure vessel.

References Cited UNITED STATES PATENTS 2,339,487 1/1944 King 103-234 2,572,082 10/1951 Welsh 210-33 2,630,249 3/1953 Bryant et al. 103-234 2,892,416 6/ 1959 Alexander 103-234 3,097,659 7/ 1963 Calvert 137-209 3,208,934 9/1965 Kingsbury 210-33 3,262,396 7/1966 Kingsbury 103-25 ROBERT M. WALKER, Primary Eicaminer. MARK NEWMAN, Examiner.

W- J, KRAUSS, AssislantExaminer. 

1. A LIQUID TRANSFER DEVICE COMPRISING A PRESSURE VESSEL HAVING; A LIQUID INLET PIPE ADAPTED FOR CONNECTION TO A SOURCE OF LIQUID TO BE METERED; A GAS OUTLET PIPE CONNECTED TO THE UPPER PORTION OF SAID PRESSURE VESSEL, FOR VENTING GAS EXPELLED FROM THE PRESSURE VESSEL WHILE THE LATTER IS BEING FILLED WITH LIQUID; A GAS INLET PIPE ADAPTED FOR CONNECTION TO A SOURCE OF PRESSURIZED GAS, AND HAVING GAS REGULATING VALVE MEANS OPERABLE TO CONTROL THE FLOW OF PRESSURIZED GAS INTO THE LIQUID-FILLED PRESSURE VESSEL; A LIQUID OUTLET PIPE CONNECTED TO THE LOWER PART OF THE PRESSURE VESSEL, AND HAVING A LIQUID METERING DEVICE PROVIDED THEREIN; AND CONTROL MEANS OPERATIVELY CONNECTED TO SAID GAS REGULATING VALVE FOR CONTROLLING THE FLOW OF GAS INTO SAID PRESSURE VESSEL RESPONSIVE TO THE METERED OUTFLOW OF SAID LIQUID THROUGH SAID OUTLET PIPE. 